What is the Difference Between Bend and Flexion?
Have you been asked to both bend and flex your horse?
Do you understand the difference?
There are several issues here that may complicate your understanding, so let’s break them down into their component parts.
I’m sure by now you’ve read or heard that what the old textbooks used to say about bend (that the horse’s spine should be uniformly curved to align to the arc of a circle or turn) has been proven to be physically impossible, as the spine is actually too inflexible to do this.
We now understand that the illusion of this curvature is created by different parts of the horse, namely:
The cervical spine (the neck) has great flexibility and can easily be positioned to conform to the arc of any circle or turn.
The middle section of the horse’s spine – the bit you sit on – (thoracic vertebrae) is highly inflexible, and cannot in reality bend.
However, by stimulating your horse’s intercostal muscles (the ones between the ribs) to contract (by applying your inside leg) your horse is able to pull the ribs on the inside of the curve closer together, and spread the ones on the outside further apart, creating what we call ‘bend in the body’.
The hind end – the lumbar region and pelvis – is also largely inflexible; the loin area has some degree of flexibility, but from the sarco-iliac joint back, the pelvis is a solid structure which no capacity for bend until you reach the tail.
In this section, bend is created from the sacro-iliac joint (where the spine meets the pelvis), and by the horse abducting the inside hind leg inward (towards the middle of the circle or turn) and forwards from the hip joint – a ball and socket arrangement that allows movement in multiple dimensions.
That’s bend in a nutshell – the ability to conform (within physical parameters) to the arc of a curve.
There are two distinct uses of the term ‘flexion’:
Longitudinal flexion is the rounding of the top line – the lifting and arching upward of the back and neck to create the round outline required for an efficient and healthy posture in which a horse may carry a rider’s weight on his back without damaging his body.
This includes flexion at the poll, such that the face is carried on or near the vertical.
Lateral flexion is the turning of the head to either left or right at the poll alone, i.e. the head turns to the side without any bend in the neck.
This is achievable because the atlas joint (the first joint where the horse’s neck and skull join) is able to move in both a longitudinal and a lateral manner.
So when you are asked to bend your horse, you will be trying to achieve all the components described above, including lateral flexion of the poll so that your horse’s head is slightly turned to the side according to the degree of bend you have in the entire length of his body.
You cannot bend your horse without flexion.
You can, however, flex your horse without bending:
- longitudinal flexion does not (necessarily) involve bend,
- you may flex your horse (turn just the head) without bending his body – this can be both a suppling request (when you ask him to relax his jaw in response to a small half halt on the bit) and as a preparation before circles, turns or a lateral movement.
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